Limit switch for hoists



Jan. 22, 1929. 7 1,699,785

' H. GEIGER ET AL LIMIT SWITCH FOR HOISTS Filed Sept. 23, 1927 I ,19 F 1'9. 1. m

0 1 S l i 4/ 40 j. T 39 1 T44 33 L 1 1 /37 INVENTORS H0/756e/ger and Ge or 50057? ATTORNEY Patented Jan. 22, 1929.

UNITED STATES PATENT OFFICE.

HANS GEIGER, 0F BERLIN-CHARLOTTENBURG, AND GEORG BAUST, OF BERLIN-STEG- LITZ, GERMANY, ASSIGNORS TO WESTINGHOUSE ELEGTRIOAND MANUFACTUR ING COMPANY, A CORPORATION OF PENNSYLVANIA.

- LIMIT SWITCH FOR HOISTS.

Application filed September 23, 1927, Serial No. 221,493, and in Germany September 25, 1926.

Our invention relates to control systems for elevators, hoists and similar apparatus.

An object of our invention is to provide a means for automatically stopping-motordriven machines at predetermined points in their operation.

Another object of our invention is to provide a stopping device for stopping motordriven machines operable between given limits of operation when the machines approach the limits of motion.

Another object of our invention is to provide a device for stopping elevators at their limits of travel.

Another object of our invention is to provide a single device for stopping an elevator at both of its limits of travel.

Another object of our invention is to provide a single device for stopping an elevator atboth of its limits of travel and wherein said device may also be operated to stop the elevator in the event of breakage or slackening of the hoisting cable.

Our invention will be described with reference to the accompanying drawings wherein,- c

Figure 1 is a schematic view of our stopping device as applied to an elevator and its hoisting mechanism,

Fig. 2 is a plan view of one of the elements of our stopping device, and A Fig. 3 is a plan view of another of the ele ments of our stopping device.

Referring to Fig. 1 of the drawings, a motor 11 operates to drive an elevator car 14 through a winding drum 12 and a cable 13 to the end of which the car is attached.

" Suitable reduction gearing, illustrated as a worm 15 mounted upon one end of the motor shaft 16 and a worm wheel 15', connects the driving motor 11 to the hoisting drum 12 for reducing the speed of the drum to a convenient degree.

Upon the other end of the motor shaft 16 is attached a sprocket wheel 17 over which passes a driving chain 18 to engage a sprocket wheel 19 of our stopping device. The sprocket wheel 19 is freely rotatable upon a suitable shaft 20 rigidly supported in suitable bearing members 21 and 22. A plurality of cam or lug members 23, 24, 25, 26 and 27 are also mounted for rotation upon the shaft 20.

Mounted upon the respective cam or lug I members 23, 24, 25, 26 and 27 are plates 28, 29, 30 and 31, which are disposed in overlapping relation. A lug 32 is mounted, as shown in Fig. 2, upon the sprocket wheel 19, for arcuate adjustment in the direction of rotation of the sprocket wheel 19, by means of a suitable screw or bolt 33. The lug 32 extends in overlapping relation to the plate 28 of the lug member 23.

The cam or lug member 27 is provided with a suitable lug'34 overlapping and engageable by the plate 31 on the lug member 26. The cam or lug member 27 is made in the general form of a disk upon which are mounted a pair of lugs 35 and 36. The lugs 35 and 36 are preferably adjustable upon the disks, as by an arcuate slot 37 and a bolt 38, (see Fig. 3) permitting adjustment of these lugs toward and away from each other.

A switch-operating device 39 is mounted upon one of the bearing members 22, as by a screw 39', and comprises a stationary contact member 40 and a (o-operating movable contact member 41. The movable contact member 41 is pivoted, as at 42, and has an extension 43 projecting into the plane of m7ovement of the lugs 35 and 36 on the disk 2 The operation of the device thus far described is as follows:

The several plates of the lug members- 23 and 27 are initially adjusted in such manner that the plates are in engagement when the elevator car is atone of its limits of travel. The driving chain 18 is then. in engagement with the sprocket wheels 17 and 19. As the car starts its movement, for example, from the lower toward the upper limit, the rotation of the motor shaft 16 drives the sprocket wheel 19 in a clockwise direction, as indicated by the arrow 44. When the sprocket wheel 19 has made a complete rotation, the lug 32 will engage the opposite face of the plate 28. Further movement of the sprocket wheel thus carries with it the lug member 23 and plate 28. At the end of a second revolution, the plate 28 will engage the plate 29 and this operation will be repeated for as many revolutions of the sprocket wheel 19 as corresponds to the distance through which the elevator car 14 inust travel, in order to move to the upper imit.

7 contact member for the switch, thus breaking the engagement between contact members 40 and 41.

The contact members 40 and 41 may be connected, in any suitable manner, to any of the control apparatus for the elevator which is designed to operate to stop the elevator. Thisapparatus may comprise the control circuits for the motor 11 or the safety grip device usually provided on elevators.

The contact members 40 and 41 may also be used to control the elevator in theevent of the slackening orbreaking of thehoisting cable 13. To accomplish this, a lever 45, mounted for rotation about the pivot 42 and frictionally engageable with contact member 41, extends to engage the cable 13 by means of a roller 46 mounted upon the outer end of the lever 45 and is initially so adjusted that the engagement of the roller 46 with a taut hoisting-cable 13 maintains the contact members 40 and 41 in engagement. A spring 47 normally tends to lift the lever 45, with the result that, should the cable become slack or break, the lever 45 would be rotated in a clockwise direction about its pivot 42, and, through its frictional engagement with the member 41, would separate the contact members 40 and 41.

On the downward movement of the eleva-' tor, the sprocket wheel 19, moving in the op posite direction, that is, counter-clockwise engages the lug 32 with the opposite side oi the plate 28, and, in turn, rotates each of the lug members 23 to 27 as the car proceeds downwardly. As the lower limit is approached, the lug 39 will again engage the lug 34 of the lug member 27, and the movement of the lug member 27 will cause its lug 36 to 'eiligage and open the switch contacts 40 and 4 Thus, it is seen that we have provided a limit-switch, which, in a single structure, combines a limiting device for stopping the elevator at both of its extreme limits of travel. The device is readily adjustable to widely variable distances of travel, since all that is required for an increased distance of travel is the suitable insertion of a greater number of the engageable -lug members 23 to 26.

With a shorter distance of travel, some of the lug members may be removed. Moreover, by using the same switch members for both limitswitch purposes and slack-cable purposes, the amount of apparatus needed is materially reduced.

The apparatus disclosed is merely illustrative, and we do not desire to be limited to the details shown, except as defined in the appended claims.

We claim as our invention:

1. A limit switch for hoists, characterized in that it is provided with an actuating member adjusted in accordance with the position of the load, the actuating member carrying with it relatively movable and mutually overlapping lugs of which the latter causes the disengagement of the contact members of the limit switch when the load travels between the extreme permissible positions.

2. A limit switch according to claim 1,.

axis of the fixed shaft, so that any desired number of such lugs may be mounted on a fixed shaft.

4. A limit switch according to claim 1, characterized in that actuation thereof is effected by a chain or by a gear wheel, whose pawl is adjustable.

5. A limit switch according to claim 1,

characterized in that the last lug is rigidly mounted on a disk, the lugs actually engaging the limit switch being adjustably mounted on the disk.

6. A limit switch according to claim 1,

characterized in that the limit switch shaft upon which are mounted the movable breaker contacts, is actuated also by the slack cable device.

7. In a stopping device for motor-driven machines, a machine operable between a plurality of. predetermined positions, a plurality of rotatable means, means'for mounting said rotatable means in a predetermined order for rotation each independent of the others, inter-engageable means on said rotatable means for sequentially engaging each of said rotatable means with the next for movement therewith, means for rotating the first of said rotatable means to correspond to the movements of said machine and means operated by movement of said last rotatable means for stopping said machine. 7

8. In a stopping device for motor-driven machines, a machine operable between a plurality of predetermined positions, a plurality of rotatable means, means for mounting said rotatable means in a predetermined order for rotation, each independent of the others, inter-engageable means on said rotatable means for sequentially engaging each of said rotatable means with the next for movement therewith at the end of one revolution, means for rotating the first of said rotatable means to correspond to the movement of said machine and means operated by movement of said last rotatable means for stopping said machine.

9. In a stopping device for elevators, an elevator operable over a path between two limits, a plurality of rotatable means, means for mounting said rotatable means in a predetermined order for rotation, each independent ot' the others, interengageable means on said rotatable means for sequentially engaging each of said rotatable means with the next for movement therewith at the end of one revolution, means for rotating the first of said rotatable means to correspond to the movement of said machine and means operated by movement of said last rotatable means for stopping said elevator when said elevator arrives at either of said limits.

10. In a sto ping device for elevators, an elevator opera e over a predetermined path,

a hoisting cable for suspending said elevator, means for stopping said elevator, means for ope 'ating said stopping means when said elevator arrives at any one of a plurality of points in said path, and means operably responsive to the slackening of said cable for also opera-ting said stopping means.

11. In a stopping device for elevators, an

elevator operable over a predetermined path, 

